/*
 * Microsoft JDBC Driver for SQL Server Copyright(c) Microsoft Corporation All rights reserved. This program is made
 * available under the terms of the MIT License. See the LICENSE file in the project root for more information.
 */

/**
 * This code is extracted from org.bouncycastle.crypto.digests.MD4Digest and modified to remove dependencies.
 */
package mssql.security.provider;

public class MD4 {
    private final byte[] xBuf = new byte[4];
    private int xBufOff;
    private long byteCount;
    private static final int DIGEST_LENGTH = 16;
    private int H1, H2, H3, H4; // IV's
    private int[] X = new int[16];
    private int xOff;

    /**
     * Standard constructor
     */
    public MD4() {
        reset();
    }

    /**
     * Copy constructor. This will copy the state of the provided message digest.
     */
    public MD4(MD4 t) {
        System.arraycopy(t.xBuf, 0, xBuf, 0, t.xBuf.length);

        xBufOff = t.xBufOff;
        byteCount = t.byteCount;

        copyIn(t);
    }

    private void copyIn(MD4 t) {
        System.arraycopy(t.xBuf, 0, xBuf, 0, t.xBuf.length);

        xBufOff = t.xBufOff;
        byteCount = t.byteCount;

        H1 = t.H1;
        H2 = t.H2;
        H3 = t.H3;
        H4 = t.H4;

        System.arraycopy(t.X, 0, X, 0, t.X.length);
        xOff = t.xOff;
    }

    public String getAlgorithmName() {
        return "MD4";
    }

    public int getDigestSize() {
        return DIGEST_LENGTH;
    }

    protected void processWord(byte[] in, int inOff) {
        X[xOff++] = (in[inOff] & 0xff) | ((in[inOff + 1] & 0xff) << 8) | ((in[inOff + 2] & 0xff) << 16)
                | ((in[inOff + 3] & 0xff) << 24);

        if (xOff == 16) {
            processBlock();
        }
    }

    protected void processLength(long bitLength) {
        if (xOff > 14) {
            processBlock();
        }

        X[14] = (int) (bitLength & 0xffffffff);
        X[15] = (int) (bitLength >>> 32);
    }

    private void unpackWord(int word, byte[] out, int outOff) {
        out[outOff] = (byte) word;
        out[outOff + 1] = (byte) (word >>> 8);
        out[outOff + 2] = (byte) (word >>> 16);
        out[outOff + 3] = (byte) (word >>> 24);
    }

    public void update(byte in) {
        xBuf[xBufOff++] = in;

        if (xBufOff == xBuf.length) {
            processWord(xBuf, 0);
            xBufOff = 0;
        }

        byteCount++;
    }

    public void update(byte[] in, int inOff, int len) {
        len = Math.max(0, len);

        //
        // fill the current word
        //
        int i = 0;
        if (xBufOff != 0) {
            while (i < len) {
                xBuf[xBufOff++] = in[inOff + i++];
                if (xBufOff == 4) {
                    processWord(xBuf, 0);
                    xBufOff = 0;
                    break;
                }
            }
        }

        //
        // process whole words.
        //
        int limit = ((len - i) & ~3) + i;
        for (; i < limit; i += 4) {
            processWord(in, inOff + i);
        }

        //
        // load in the remainder.
        //
        while (i < len) {
            xBuf[xBufOff++] = in[inOff + i++];
        }

        byteCount += len;
    }

    public void finish() {
        long bitLength = (byteCount << 3);

        //
        // add the pad bytes.
        //
        update((byte) 128);

        while (xBufOff != 0) {
            update((byte) 0);
        }

        processLength(bitLength);

        processBlock();
    }

    public int doFinal(byte[] out, int outOff) {
        finish();

        unpackWord(H1, out, outOff);
        unpackWord(H2, out, outOff + 4);
        unpackWord(H3, out, outOff + 8);
        unpackWord(H4, out, outOff + 12);

        reset();

        return DIGEST_LENGTH;
    }

    /**
     * reset the chaining variables to the IV values.
     */
    public void reset() {
        byteCount = 0;

        xBufOff = 0;
        for (int i = 0; i < xBuf.length; i++) {
            xBuf[i] = 0;
        }

        H1 = 0x67452301;
        H2 = 0xefcdab89;
        H3 = 0x98badcfe;
        H4 = 0x10325476;

        xOff = 0;

        for (int i = 0; i != X.length; i++) {
            X[i] = 0;
        }
    }

    //
    // round 1 left rotates
    //
    private static final int S11 = 3;
    private static final int S12 = 7;
    private static final int S13 = 11;
    private static final int S14 = 19;

    //
    // round 2 left rotates
    //
    private static final int S21 = 3;
    private static final int S22 = 5;
    private static final int S23 = 9;
    private static final int S24 = 13;

    //
    // round 3 left rotates
    //
    private static final int S31 = 3;
    private static final int S32 = 9;
    private static final int S33 = 11;
    private static final int S34 = 15;

    /*
     * rotate int x left n bits.
     */
    private int rotateLeft(int x, int n) {
        return (x << n) | (x >>> (32 - n));
    }

    /*
     * F, G, H and I are the basic MD4 functions.
     */
    private int F(int u, int v, int w) {
        return (u & v) | (~u & w);
    }

    private int G(int u, int v, int w) {
        return (u & v) | (u & w) | (v & w);
    }

    private int H(int u, int v, int w) {
        return u ^ v ^ w;
    }

    protected void processBlock() {
        int a = H1;
        int b = H2;
        int c = H3;
        int d = H4;

        //
        // Round 1 - F cycle, 16 times.
        //
        a = rotateLeft(a + F(b, c, d) + X[0], S11);
        d = rotateLeft(d + F(a, b, c) + X[1], S12);
        c = rotateLeft(c + F(d, a, b) + X[2], S13);
        b = rotateLeft(b + F(c, d, a) + X[3], S14);
        a = rotateLeft(a + F(b, c, d) + X[4], S11);
        d = rotateLeft(d + F(a, b, c) + X[5], S12);
        c = rotateLeft(c + F(d, a, b) + X[6], S13);
        b = rotateLeft(b + F(c, d, a) + X[7], S14);
        a = rotateLeft(a + F(b, c, d) + X[8], S11);
        d = rotateLeft(d + F(a, b, c) + X[9], S12);
        c = rotateLeft(c + F(d, a, b) + X[10], S13);
        b = rotateLeft(b + F(c, d, a) + X[11], S14);
        a = rotateLeft(a + F(b, c, d) + X[12], S11);
        d = rotateLeft(d + F(a, b, c) + X[13], S12);
        c = rotateLeft(c + F(d, a, b) + X[14], S13);
        b = rotateLeft(b + F(c, d, a) + X[15], S14);

        //
        // Round 2 - G cycle, 16 times.
        //
        a = rotateLeft(a + G(b, c, d) + X[0] + 0x5a827999, S21);
        d = rotateLeft(d + G(a, b, c) + X[4] + 0x5a827999, S22);
        c = rotateLeft(c + G(d, a, b) + X[8] + 0x5a827999, S23);
        b = rotateLeft(b + G(c, d, a) + X[12] + 0x5a827999, S24);
        a = rotateLeft(a + G(b, c, d) + X[1] + 0x5a827999, S21);
        d = rotateLeft(d + G(a, b, c) + X[5] + 0x5a827999, S22);
        c = rotateLeft(c + G(d, a, b) + X[9] + 0x5a827999, S23);
        b = rotateLeft(b + G(c, d, a) + X[13] + 0x5a827999, S24);
        a = rotateLeft(a + G(b, c, d) + X[2] + 0x5a827999, S21);
        d = rotateLeft(d + G(a, b, c) + X[6] + 0x5a827999, S22);
        c = rotateLeft(c + G(d, a, b) + X[10] + 0x5a827999, S23);
        b = rotateLeft(b + G(c, d, a) + X[14] + 0x5a827999, S24);
        a = rotateLeft(a + G(b, c, d) + X[3] + 0x5a827999, S21);
        d = rotateLeft(d + G(a, b, c) + X[7] + 0x5a827999, S22);
        c = rotateLeft(c + G(d, a, b) + X[11] + 0x5a827999, S23);
        b = rotateLeft(b + G(c, d, a) + X[15] + 0x5a827999, S24);

        //
        // Round 3 - H cycle, 16 times.
        //
        a = rotateLeft(a + H(b, c, d) + X[0] + 0x6ed9eba1, S31);
        d = rotateLeft(d + H(a, b, c) + X[8] + 0x6ed9eba1, S32);
        c = rotateLeft(c + H(d, a, b) + X[4] + 0x6ed9eba1, S33);
        b = rotateLeft(b + H(c, d, a) + X[12] + 0x6ed9eba1, S34);
        a = rotateLeft(a + H(b, c, d) + X[2] + 0x6ed9eba1, S31);
        d = rotateLeft(d + H(a, b, c) + X[10] + 0x6ed9eba1, S32);
        c = rotateLeft(c + H(d, a, b) + X[6] + 0x6ed9eba1, S33);
        b = rotateLeft(b + H(c, d, a) + X[14] + 0x6ed9eba1, S34);
        a = rotateLeft(a + H(b, c, d) + X[1] + 0x6ed9eba1, S31);
        d = rotateLeft(d + H(a, b, c) + X[9] + 0x6ed9eba1, S32);
        c = rotateLeft(c + H(d, a, b) + X[5] + 0x6ed9eba1, S33);
        b = rotateLeft(b + H(c, d, a) + X[13] + 0x6ed9eba1, S34);
        a = rotateLeft(a + H(b, c, d) + X[3] + 0x6ed9eba1, S31);
        d = rotateLeft(d + H(a, b, c) + X[11] + 0x6ed9eba1, S32);
        c = rotateLeft(c + H(d, a, b) + X[7] + 0x6ed9eba1, S33);
        b = rotateLeft(b + H(c, d, a) + X[15] + 0x6ed9eba1, S34);

        H1 += a;
        H2 += b;
        H3 += c;
        H4 += d;

        //
        // reset the offset and clean out the word buffer.
        //
        xOff = 0;
        for (int i = 0; i != X.length; i++) {
            X[i] = 0;
        }
    }
}
